Aqueous 1-methoxy-2-propanol has been employed as coolant in ebullient cooling systems for heavy-duty stationary engines and for standard circulating cooling systems in mobile internal combustion engines, including rotary engines.
Common antifreezes based on methanol, ethanol, propanol, ethylene glycol, other glycols or polyglycols or glycerine have been inhibited with soluble phosphate salts in combination with borate salts and optionally mercaptobenzothiazole at pH of between about 7.5 and 9; U.S. Pat. No. 2,384,553. Phosphate or borate salts of alkanolamines have also been employed in coolants as inhibitors; U.S. Pat. No. 1,992,689. In propylene glycol based aqueous coolant, 1 percent dipotassium phosphate has been recommended as a corrosion inhibitor. One older teaching, Canadian Pat. No. 621,174, mentions that minor amounts of conventional antioxidants and corrosion inhibitors may be employed in methoxypropanol, e.g., phenols, amines, phosphates, mercaptans and sulfides. A later teaching notes that common inhibitors for glycol coolants are not soluble in concentrated methoxypropanol; Soap and Chem. Specialties, (Oct., 1967), p. 76. Subsequently, U.S. Pat. 3,553,137 teaches that alkali metal nitrites, piperazines and benzotriazole are useful as corrosion inhibitors for aqueous methoxypropanol coolant.